1. Field of the Invention
The present invention relates to a method of manufacturing an integrated circuit, and more particularly, to a manufacturing method of gate oxide layers with different thicknesses.
2. Description of Related Art
With the thriving of the electronics industry in recent years, the integrated circuit chip has been widely used. In order to meet the cutting-edge demand from the electronics industry, many techniques regarding the manufacturing of the semiconductor develop rapidly as well.
In integrated circuit devices, different circuits need different circuit devices with different basic operational characteristics to coordinate closely with. In order to meet the demands for competitive edges and diversity of the circuit device, certain circuits need to be equipped with devices having gate oxide layers with different thicknesses at the same time to meet the requirements of different operational voltages. Hence, the need for multiple gate oxide layer thicknesses arises. Generally, devices of different voltages, such as high voltage (HV) devices and low voltage (LV) devices, exist simultaneously on the same chip. A high voltage device requires a thicker gate oxide layer to withstand the high voltage operation environment, whereas a thinner gate oxide layer in a low voltage device can well withstand the low voltage operation environment.
In view of the current manufacturing process, when the thicknesses of gate oxide layers vary greatly, some difficulties would emerge in the subsequent manufacturing process. Therefore, how to manufacture gate oxide layers having different thicknesses and maintain the quality of the layers so that the efficiency of devices is not affected has become a primary issue that urgently needs solving.